Thallus dark red-orange to medium orange; lobes rounded or finely divided, 0.2-0.6 mm wide, flat to somewhat convex, ascending to erect (especially in the northwest) or mostly horizontal (especially in the southeast), with mealy soredia on the edge of the lower surface, not forming hoods; lower surface white, with few rhizines or holdfasts. Apothecia rarely seen; pycnidia common, resembling dark orange pimples; conidia baciliform, 3-4.5 um long. HABITAT: Mostly on bark, sometimes on wood, and rarely on rock. COMMENTS: Among the sorediate species of Xanthoria, X. fulva, X. ulophyllodes, and X.oregana are most similar to X. fallax. Xanthoria fulva has narrower, more ascending lobes and lacks rhizines, and the grandular soredia are mainly on the lower surface. Xanthoria fulva and X. oregana have soredia on the lower surface of the lobes, and the pycnidia are more prominent.